In the report, the researchers found “strong evidence for a causative role for traffic-related air pollution and premature death,” particularly from heart attacks and strokes. PM2.5 is emitted directly, and it is also produced by secondary formation, as sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions contribute to the formation of sulfate and nitrate particles. The report indicates that exposure to PM2.5 also causes other health effects such as asthma attacks, and other respiratory illnesses.Traffic congestion is a significant issue in virtually every urban area in the United States and around the world.

“Anyone who spends any time commuting knows that the time and fuel wasted while sitting in traffic can not only be annoying, but can lead to real economic costs,” according to the report’s summary. “An examination of the peer-reviewed literature shows that there are many previous analyses that estimate the economic costs of congestion based on fuel and time wasted, but that these studies don’t include the costs of the potential public health impacts. Sitting in traffic leads to higher tailpipe emissions which everyone is exposed to, and the and the economic costs of those exposures have not been explored.”